1. Field of the Invention
The present invention relates to devices for applying strips of material to a surface, and in one aspect to devices for applying strips of reflex-light reflective material around tire casings.
2. Description of the Prior Art
Tires including reflex-light reflective strips around their sidewalls (as taught in U.S. Pat. No. 2,382,908) have found particular acceptance for use on bicycles and motorcycles to provide a measure of safety when the cycle is operated after dark. Such tires are typically constructed by adhering parallel strips of an uncured elastomer (such as neoprene or natural rubber) supporting a layer of reflex-light reflective elements to the outer surface of an unvulcanized tire casing. The tire casing is then vulcanized in a tire mold to form a completed tire having a U-shaped cross section with tread, embossed brand and size information and the strips permanently incorporated in its sidewalls.
Known prior art devices for applying such strip material to an unvulcanized tire casing includes the device illustrated in Drawing No. TR-175 which is available from the Special Enterprises Department of Minnesota Mining and Manufacturing Company, Saint Paul, Minn., and the devices described in U.S. Pat. Nos. 3,899,383 and 3,944,457. These devices work well for the application of reflective strip material to bicycle tires. They are not as suitable for the application of reflective strip material to motorcycle tires, however. The greater width of such strips (e.g. 1/2 inch as opposed to 3/16 inch for bicycle tires) dictates the use of a more positive liner removal means than these devices provide. Also the reflex-light reflective elements in strip material for use on motorcycle tires are coated with a protective layer (e.g. latex) which protects the reflex-light reflective elements from being coated with a dark paint-like mold release agent sprayed over the tire before it is placed in the tire mold and prevents degradation of the reflectivity of the elements which occurs if they are exposed during the molding process. This protective layer (which is stripped away after the tire is molded) causes much greater sliding friction than the surface of the elements themselves which element surface is exposed on the strips used in the aforementioned devices. Thus a device for applying such strip material to motorcycle tires should make no sliding contact with the protective layer and yet must accurately guide the strip material to insure that the edges of the applied strip will be straight and parallel and will be closely aligned (e.g. within 0.030 inch) when the ends of the applied strip meet so that the strips will be smoothly concentric after the tire is molded. Also the device must have a highly accurate system for providing the amount of overlap of the ends of the applied strips (e.g. no more than 1/8 inch) to insure a proper appearance of the strips at their ends in the molded tire.